A resist-coated substrate for mask manufacturing may be structured by a particle beam writing apparatus. An exposure of the resist includes a sequence of shots. During each shot a particle beam, for example an electron beam, an ion beam or another particle beam, is directed to the resist-coated substrate. The resist is sensitive to an irradiation with the particles and changes its chemical properties. A particle beam pattern generator determines size, shape and dose for each single shot based upon a layout data pattern. The details of each shot, for example shot area, shape, dose and exposure sequence, and hence the control of the particle beam writing apparatus determine the required writing strategy.
For a vector scan shaped particle beam writing apparatus, a shot definition includes positioning the particle beam and selecting an aperture of an illumination system to determine shape and size of the shot area. Then the particle beam is turned on for a time calculated from the dose required for patterning the resist in the respective spot area and from a nominal particle beam density, for example a nominal current density. Dose deviations may result, for example, in line width aberrations. A need exists for a particle beam exposure method with high throughput and high yield.
A further need exists for improved particle beam writing methods compensating, for example, resist heating effects or dose variations, at high throughput.
Although the invention is illustrated and described herein as embodied in a particle beam writing method, a particle beam writing apparatus, and a maintenance method for the same, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. Additionally, well-known elements of exemplary embodiments of the invention will not be described in detail or will be omitted so as not to obscure the relevant details of the invention.
Other features that are considered as characteristic for the invention are set forth in the appended claims. As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one of ordinary skill in the art to variously employ the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the invention. While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward. The figures of the drawings are not drawn to scale.
Before the present invention is disclosed and described, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The terms “a” or “an”, as used herein, are defined as one or more than one. The term “plurality,” as used herein, is defined as two or more than two. The term “another,” as used herein, is defined as at least a second or more. The terms “including” and/or “having,” as used herein, are defined as comprising (i.e., open language). The term “coupled,” as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically.
As used herein, the term “about” or “approximately” applies to all numeric values, whether or not explicitly indicated. These terms generally refer to a range of numbers that one of skill in the art would consider equivalent to the recited values (i.e., having the same function or result). In many instances these terms may include numbers that are rounded to the nearest significant figure.
Features and advantages of embodiments of the invention will be apparent from the following description of the drawings. Emphasis is placed upon illustrating the principles. The drawings are not to scale. Features of the embodiments may be combined with each other unless they exclude each other.